Most home laundry powders contain a peroxide compound, such as sodium perborate or sodium percarbonate, for improving the elimination of numerous stains and restoring the initial whiteness to the textile wash due to its laundering effect. Likewise, the textile industry generally uses baths containing a peroxide compound, such as hydrogen peroxide or sodium perborate, for the bleaching of unbleached textiles.
To obtain a maximum bleaching or laundering effect, it is necessary to effectively stabilize the peroxide compound. This stabilizing effect can be obtained by adding, to the washing bath, magnesium silicate which slows down the decomposition rate of the peroxide compound. The magnesium silicate makes it possible to retain the maximum active oxygen function in the bleaching bath above a temperature on the order of 60.degree. C., due to which the peroxide compound attains its full effectiveness.
The magnesium silicate is added to the laundry powder either in the preformed state or is formed chemically "in situ" from the reaction of sodium silicate and a magnesium salt. The "in situ" formation process generally produces a rough feel in the laundered fabric, causes resistance to dyeing due to the lack of affinity of the fabric for water, and results in deposits to form in the bleaching or laundering machines which cause mechanical wear and weakening in the strength of the bleached textile fibers.
According to U.S. Pat. No. 3,860,391, assigned to Benkiser-Knapsak Company, a process of bleaching textile fibers in a bath without the use of a silicate has been proposed, in which bath the pH is adjusted to be between 9 and 12, and to which a stabilizing agent is added, the stabilizing agent consisting of a mixture of a hydroxyaliphatic compound containing 2 to 6 carbon atoms and a phosphonic acid chosen from the group consisting of an amino alkylene phosphonic acid, a hydroxyalkane phosphonic acid, a soluble salt of these acids and mixtures thereof; in these baths the peroxide compound is hydrogen peroxide.
The French Pat. No. 2,396,114, in the name of the company known as Manufacture de Produits Chimiques Protex, proposed various compositions intended to stabilize the hydrogen peroxide baths, an exemplary stabilizing composition, consisting, in a concentrated form, of stable and liquid formulations composed of sodium silicate and a magnesium complex, said magnesium complex being formed from phosphonic acids.
The French Pat. No. 2,420,593, in the name of Kao Soap, directed to bleaching compositions which do not alter the color of treated textiles, proposes to add, particularly to sodium percarbonate or to the additive product of tetrasodium 1,1,2,2-ethane tetracarboxylate and H.sub.2 O.sub.2, at least one organophosphonic and organoacetic compound.
On the other hand, the French Pat. No. 2,140,213, in the name of Monsanto, relates to a stabilizing agent intended to reduce the decomposition of a peroxide compound contained in an aqueous alkaline solution. This agent is formed from a mixture of 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP), a nitrilotriacetic acid (NTA), and water-soluble salts, such as magnesium sulfate.
The French Pat. No. 1,420,462, in the name of the applicants herein, relates to a process of stabilizing peroxide compounds by using magnesium silicate in the bleaching and laundering of textile fibers and fabrics, according to which the magnesium silicate is preformed in the colloidal state prior to such use. According to an exemplary method of practicing the process, the magnesium silicate, which is preformed in the colloidal state, is used in association with small quantities of a dimagnesium salt of ethylenediamine tetraacetic acid.